Carbon brakes as are fitted to many modem aircraft that are designed to carry large passenger or cargo payloads. Such brakes rely on the use of a carbon composite material to serve as friction material as well a heat sink. A stack of carbon rotor disks and carbon stator disks are coaxially arranged in an alternating sequence along a wheel's axis wherein the rotor disks are rotationally keyed to the wheel while the stator disks are keyed to the stationary axle. Braking force is generated by the pressurization of piston actuators that are configured to compress the stack between a pressure plate and a backing plate to thereby cause the friction surfaces of adjacent disks to engage one another. While carbon brakes are preferred for weight and performance reasons over steel brakes, the cost of replacing the stack as a function of landing cycles between replacements is much higher than for steel brakes.
In contrast to conventional steel brakes for which brake life is largely determined by the total amount of energy that is absorbed, carbon brakes wear as a function of the number of times the brakes are applied as wear is highest upon initial application when the brake temperature is low. Consequently, most wear tends to occur during taxiing as the brakes may routinely be applied dozens of times in negotiating the taxiways between the runway and the gate and during the stop-and-go that may be encountered in the queue for take off.
Efforts to reduce the number of brake applications and hence the wear rate of carbon brakes have to date focused on disabling one or more brakes during low energy brake applications. As such, individual brakes are subject to a lower number of brake applications while the increased braking load during each application has no adverse effect on wear. Systems have been described that determine the sequence of brake disablements so as to achieve an even wear rate amongst the various braked wheels without compromising stopping ability and without adversely affecting the stability of the aircraft. Such systems add substantial complexity and cost to an aircraft braking system and retrofitting existing aircraft requires the expenditure of a significant amount of time and effort.
An alternative approach for reducing carbon brake wear and more specifically, for reducing the number of brake applications during a take-off and landing cycle is needed that is inexpensive and simple and is easily adapted to existing aircraft. Ideally, such system should be adaptable to any aircraft and without modification of the existing brake system.